Ah, the apostrophe. It causes a lot of trouble for such a little squiggle on the page. That’s partly because the apostrophe has more than one job. But it’s easy enough to use once you know how.

Guide to apostrophes

Step One: Standing In

The apostrophe’s first job is to stand in for a letter which has been removed for the sake of convenience, such as when where is becomes where’s. These words are known as contractions.

For example, “That is a nice frock, dear,” becomes “That’s a nice frock, dear.” That is has been contracted to that’s and the apostrophe is standing in for the letter i.

Step Two: Who Owns What

The apostrophe’s second job is to indicate who owns what in a sentence. This is called a possessive apostrophe and can either be singular (something belongs to one person or thing) or plural (something belongs to a group). The easiest way to show how it’s used is with a few examples.

Harry’s books are on the desk.
The apostrophe shows that the books belong to Harry.

The bird’s eggs were gathered from the nest.
The apostrophe shows that the eggs belonged to the bird.

If the eggs belonged to several birds, the apostrophe would move:
The birds’ eggs were gathered from the nests.

The children’s books are on the desk.
The apostrophe shows that the books belong to the children.

Note: the apostrophe goes before the s because the word children is plural. If you put the apostrophe after the s, the books would belong to the “childrens”, which is nonsense.

Step Three: Its and It’s

This is one that people often get wrong but it’s simple if you remember this: If you mean it is, use it’s. Otherwise, use its.

It’s is a contraction, a shortened form of it is.
It’s a nice day. It’s no good remembering things the day after the exam. It’s a long way to Tipperary.

Its stands in for a noun in a sentence to prevent repetition.
The cat chased its tail. The business said its results were brilliant. The dog ate its dinner.

Without its, we’d have to say the cat chased the cat’s tail, the business said the business’s results were brilliant and so on, which is clumsy and repetitive.

All Done

So that’s it. Apostrophes in three easy steps. Why not bookmark the page so you can come back and refresh your memory from time to time. Meantime, go forth and punctuate.